We are in the process of studying the regulation of ribosomal RNA synthesis in Escherichia coli and the regulation of "anaerobically" induced mRNA in Rholopseudomonas spheroides. Our studies include the in vitro biosynthesis of rRNA using purified DNA template enriched for rDNA and purified E. coli RNA polymerase. We are examining the nature of the product formed and the regulation of its synthesis. Our in vivo work involves the expression of E. coli rDNA in proteus mirabilis. We are examining the nature of the E. coli product made from the point of view of its structure, amounts and functionality. We are also examining the regulation of this rDNA in a foreign genetic background. In R. spheroides we have been able to correlate specific physiologic respone with the presence and/or absence of a particular species of tRNA. The primary structure of these isoaccepting tRNA species are being examined.